Pacific Northwest Mountain Grassland

EVT 7138North Pacific Montane Grassland
CES204.100GNRHerbGrassland
Summary
This ecological system includes open dry meadows and grasslands on the west side of the Cascades Range and northern Sierra Nevada. They occur in montane elevations up to 3500 m (10,600 feet). Soils tend to be deeper and more well-drained than the surrounding forest soils. Soils can resemble prairie soils in that the A-horizon is dark brown, relatively high in organic matter, slightly acidic, and usually well-drained. Dominant species include Elymus spp., Festuca idahoensis, and Nassella cernua. These large-patch grasslands are intermixed with matrix stands of red fir, lodgepole pine, and dry-mesic mixed conifer forests and woodlands.
Source: NatureServe Explorer
Distribution
This system is found on the west side of the Cascades Range and northern Sierra Nevada, in montane elevations up to 3500 m (10,600 feet).
Source: NatureServe Explorer
Ecologically Associated Plant Species

Plant species that characterize this ecosystem type, organized by vegetation stratum. These are species ecologically associated with the ecosystem, not confirmed present in any specific area.

Herb (field)

Elymus elymoides, Festuca idahoensis, Gilia capillaris, Nassella cernua
Source: NatureServe Ecological System assessment
Ecologically Associated Animals (5)

Animal species ecologically associated with this ecosystem type based on NatureServe assessment. These are species whose habitat requirements overlap with this ecosystem, not confirmed present in any specific roadless area.

Mammals (5)

Common NameScientific NameG-Rank
Yellow-bellied MarmotMarmota flaviventrisG5
Montane VoleMicrotus montanusG5
Mountain Pocket GopherThomomys monticolusG5
Northern Pocket GopherThomomys talpoidesG5
Belding's Ground SquirrelUrocitellus beldingiG5
Source: NatureServe Ecological System assessment
At-Risk Species Associated with this Ecosystem (1)

Species with conservation concern that are ecologically associated with this ecosystem type. G-Rank indicates global conservation status: G1 (critically imperiled) through G5 (secure). ESA status indicates U.S. Endangered Species Act listing.

Common NameScientific NameG-RankESA Status
Nodding NeedlegrassNassella cernuaG3G4--
Source: NatureServe Ecological System assessment
State Conservation Ranks (3)

Subnational conservation status ranks (S-ranks) assigned by Natural Heritage Programs in each state where this ecosystem occurs. S1 indicates critically imperiled at the state level, S2 imperiled, S3 vulnerable, S4 apparently secure, and S5 secure. An ecosystem may be globally secure but imperiled in specific states at the edge of its range.

StateS-Rank
CASNR
NVSNR
ORSNR
Roadless Areas (26)

Inventoried Roadless Areas where this ecosystem is present, identified from LANDFIRE 2024 Existing Vegetation Type spatial analysis. Coverage indicates the proportion of each area occupied by this ecosystem type.

Oregon (26)

AreaForestCoverageHectares
CornpatchWillamette National Forest49.9%1,484.37
OlallieMt. Hood National Forest40.4%1,244.25
CharltonDeschutes National Forest32.3%922.5
ElkhornWillamette National Forest29.0%1,099.89
Opal CreekWillamette National Forest22.1%484.11
Waldo - Many PrariesWillamette National Forest18.1%189.54
Mt. Jefferson AdditionMt. Hood National Forest17.1%11.16
Waldo - Salmon CreekWillamette National Forest14.0%180.72
Charlton ButteWillamette National Forest10.8%132.39
Waldo - FujiWillamette National Forest10.8%666.45
Mt. JeffersonDeschutes National Forest7.1%65.25
Bull Of The WoodsMt. Hood National Forest6.0%214.38
Williams CreekUmpqua National Forest5.7%135.54
Cougar BluffUmpqua National Forest5.4%120.96
Mt. HagenWillamette National Forest4.9%127.17
Sky Lakes AWinema National Forest4.0%64.62
Mt. BaileyUmpqua National Forest3.9%291.78
Waldo - LakeWillamette National Forest3.9%46.71
Rogue - Umpqua DivideRogue River National Forests3.4%91.44
Echo MountainWillamette National Forest3.2%105.93
LastUmpqua National Forest2.3%72.81
Calf - Copeland CreekUmpqua National Forest2.2%138.69
Canton CreekUmpqua National Forest1.9%51.39
Sky Lakes BWinema National Forest1.6%61.02
Chucksney MountainWillamette National Forest1.0%64.98
Mt. Hood AdditionsMt. Hood National Forest0.7%37.71
Methodology and Data Sources

Ecosystem classification: Ecosystems are classified using the LANDFIRE 2024 Existing Vegetation Type (EVT) layer, mapped to NatureServe Terrestrial Ecological Systems via a curated crosswalk. Each EVT is linked to the USNVC (U.S. National Vegetation Classification) hierarchy through pixel-level co-occurrence analysis of LANDFIRE EVT and NatureServe IVC Group rasters across all roadless areas.

Vegetation coverage: Coverage percentages and hectares are derived from zonal statistics of the LANDFIRE 2024 EVT raster intersected with roadless area boundaries.

Ecosystem narratives and community species: Sourced from the NatureServe Explorer API, representing professional ecological assessments of vegetation composition, environmental setting, dynamics, threats, and characteristic species assemblages.

IVC hierarchy: The International Vegetation Classification hierarchy is sourced from the USNVC v3.0 Catalog, providing the full classification from Biome through Association levels.

Component associations: Plant community associations listed as components of each NatureServe Ecological System. Association data from the NatureServe Explorer API.

State ranks: Conservation status ranks assigned by NatureServe member programs in each state where the ecosystem occurs.